I get 30-31 highway mpg in my manual trans M2 at highway speeds of 70-75 or so. As long as I don't stomp on the throttle I've been truly impressed with the fuel mileage. My long term (30 month, 40k miles) fuel mileage is 25 mpg INCLUDING 30 track days plus 5 days of lake ice racing. Fuel mileage on track days is 7-8 mph. My daily commute is 2/3 highway and 1/3 secondary roads.

You must be the world record holder for fuel economy, considering that these cars get around 20-21 mpg combined highway and around town driving. Maintaining 30-31 on the highway would take quite a long tailwind I think....lol